2001 V70 XC, battery current draw in ignition position II

Post by **jonesg** » 15 Jul 2026, 03:09

scot850 wrote: 14 Jul 2026, 08:30 Is it safe to have a charger putting out 20A attached to a battery connected to a car?

Neil.

when I put my charger in start mode it boosts at 50 amps.

Post by **jonesg** » 15 Jul 2026, 03:13

scot850 wrote: 14 Jul 2026, 08:41 Off a car charging to 30A or so is ok. But while attached to a car?? I'm thinking Volvo tell you to have the key on to Pos II when reconnecting a battery to lessen the chances of frying the electrics, and even you alternator only charges at 14.5A or so.

Neil.

pos ii when hooking up the battery is to prevent the airbag going off in your face.

Post by **scot850** » 15 Jul 2026, 08:12

But when your charger starts at 50A, is the battery left connected to your car?

Neil.

Post by **vtl** » 15 Jul 2026, 08:24

scot850 wrote: 15 Jul 2026, 08:12 But when your charger starts at 50A, is the battery left connected to your car?

The battery provides hundreds of Amps to starter every time you start the engine. It perhaps would not even start with 50 Amps. Similarly, alternator can provide north of 100 Amps to the battery. In our Volvos it is typically 140 or 160 Amps.

Post by **jonesg** » 15 Jul 2026, 12:10

scot850 wrote: 15 Jul 2026, 08:12 But when your charger starts at 50A, is the battery left connected to your car?

Neil.

Yeh, I've done it both ways.

JeffreP · Post by **JeffreP** » 17 Jul 2026, 02:32

jonnycycles wrote: 12 Jul 2026, 16:07 I recently got a vida setup for my PC, saw some warnings about being cautious not to drain the battery while using but thought I'll just be few minutes, no big deal. A short time later: dead battery.

After re-charging and using the charger while using Vida it took a little while longer, but still dead battery.

After some investigating I found the car draws 14 amps of current when the key is is position 2. Pulling the parking light fuse and battery fuse (aftermarket radio that's always on) I got it down to 10 amps, but this is still more than my 6 amp charger can provide.

I'll be honest, I have no idea as I never spent much time hanging out with the ignition in position II, but what is a normal current draw here? Should I dig deeper into this, or just get a bigger charger?

14A with the ignition in position II doesn't sound unreasonable on many Volvos. In that mode you've got multiple control modules awake, the instrument cluster, CEM, fuel system electronics, VIDA communication, and often the radiator fan or climate control modules can wake up intermittently. VIDA itself keeps a lot of modules from going to sleep, so the current stays much higher than the normal resting draw.

A 6A charger usually isn't enough to keep up with that load, which is why the battery still slowly discharges. Most people who use VIDA regularly connect a 10–20A power supply or battery maintainer designed for diagnostics rather than a small trickle charger.

I'd only start chasing a fault if you're seeing an unusually high draw with the ignition off after all the modules have had time to go to sleep. For diagnostic sessions with the key in position II, upgrading to a higher-capacity charger is probably the simplest solution.